1. Field of the Invention
The present invention relates generally to a method and system for transmitting a multimedia message transmitted from the transmitting mobile station of a higher version to a receiving mobile station of a lower version and, more particularly, to a method and system for reconstructing a multimedia message in a form appropriate for the specification of a receiving mobile station and transmitting the reconstructed multimedia message to the receiving mobile station.
2. Description of the Related Art
Recently, Multimedia Messaging Service (MMS) transmitting multimedia messages through mobile stations has been widely used. In the early stages of the service, multimedia messages including still images were serviced. However, in these days, multimedia messages including various types of data such as moving images are being serviced.
MMS is a service defined by international standards, such as 3rd Generation Partnership Project (3GPP) Technical Specification (TS) 22.140 and 23.140. The MMS is capable of transmitting and receiving short messages and various multimedia data (e.g. voice, image, audio and video data) between stations.
The MMS, defined by the international standards, adopts a store-and-forward method as a message transmission method. A multimedia message is transmitted with encapsulated media contents, information required to describe the media contents, and address information required to identify a message recipient. The multimedia message is transmitted from a transmitting mobile station to a Multimedia Messaging Service Center (MMSC). Furthermore, the MMSC informs a receiving mobile station of the storing of the multimedia message. The multimedia message stored in the MMSC is transmitted to the receiving mobile station in response to a request from the receiving mobile station.
The MMS is classified into a service capable of transmitting only still images, a service capable of transmitting moving images, and a Synchronized Multimedia Integration Language (SMIL) MMS capable of providing various display functions for each type of multimedia data, according to the types of the serviced multimedia data. With the development of the services, some stations became unable to reproduce the transmitted multimedia messages.
That is, in the case of constructing an MMS message using a station capable of supporting the SMIL MMS, and transmitting the MMS message to a conventional Wireless Application Protocol (WAP) receiving mobile station having a lower bandwidth and a lower specification, the receiving mobile station cannot reproduce the large volume photo images included in the SMIL MMS message due to a limitation in the WAP buffer size of the receiving mobile station.
To solve the problem, transcoding technology was proposed. Transcoding refers to the technology of searching the profile of a receiving mobile station, converting a requested MMS message to be optimum for the receiving mobile station, and transmitting the optimum MMS message to the receiving mobile station.
However, satisfactory data conversion results could not be achieved even though format conversion, resolution conversion and chord conversion were performed on the media data (e.g., images, animations and audio) included in a multimedia message using the transcoding technology. The reason is as follows. In the case of JPEG images, format and resolution conversion is possible. However, in the case of Simple Image Solution (SIS) images, format conversion is possible (only between high quality SIS and low one) but resolution conversion is impossible. Additionally, in the case of MA-x (MA-1, MA-2, MA-3, MA-4, or MA-5) audio, format and chord conversion is impossible. Accordingly, even in the MMS system that uses the transcoding technology, the receiving mobile station has a limitation in the reproduction of the multimedia message if a SIS image or MA-x audio is included in the multimedia message transmitted to the receiving mobile station.